I have an Outback temp sensor attached to my FX3048 master inverter. Among other things, this allows me to see the 'temperature adjusted' battery voltage on the Mate when the batteries are being charged.

My assumption has been (based on my reading of the manuals) that one temp. sensor attached to the FX master inverter would allow any other chargers (like my FM80 and MX60) to take the battery temps into account. But this appears to not be the case. Today I was taking advantage of the sunlight to do an EQ charge. And I noticed what I had noticed on a previous solar EQ cycle--that while the Mate gave the temp. compensated voltage as 62.4, the FM80 and MX60 were showing battery voltage at 61.5. Thus the CC's were still in bulk EQ mode when, had the charge been coming from the genset, the FX inverters would have been counting down the EQ time.

I have two questions: First is, should I be concerned? Perhaps when all is said and done it doesn't matter unduly--but I do worry about the CC's not being able to take battery temperature into account, esp. during the hotter summer months. Secondly, as I have a second Outback temp sensor sitting idle, would it mix up the system to attach it one of the CC's? (If so, I presume the FM80 would be the choice?)

Grateful as always for the wisdom of the community. (Though still waiting for confirmation about my diversion load thinking in my last post...)

To rfonda, your understanding is my understanding and reflects how I have understood the manuals. This is why I am having the conversation with OB.

To SteveHiggins: Very nice to have the battery mfr. perspective. Thanks! What I read in the Mate manual is this: "batt temp: this value, which reflects the battery temperature, is used by the charger when an RTS is connected to the FX" (p. 44 in Mate manual).

The temp. sensor plugs into my Master FX inverter which allows the charging to be adjusted according to temperature. I have watched this take place. Almost two years ago, my lack of understanding about my batteries had led to heavy sulphation. To work at restoring them, I took them through a series of carefully monitored eq cycles. As the battery temps rose, I could observe the charge amps backing off. (I can report that, with lots of good advice from this forum, my batteries seem to be in quite good condition, now going on 11 years and counting.)

I do monitor the SG of the batteries. But I also run a 2hr. EQ cycle about once every 6 weeks or so, irrespective of SG (which typically is within .05 to .15 across the bank).

Had a helpful call from OB technical support this morning, directing me to p. 103 of the FM60/FM80 manual, where there is a section on temperature compensation and charging. Don't know how I had missed it, but it very clearly states:

"The FLEXmax controller, when equipped with the Remote Temperature Sensor (RTS) will compensate for temperature. The RTS is attached to a single battery near the center of the bank. When charging, the RTS will increase or decrease the charge voltage by 5 mV per degree Celsius per battery cell. This setting affects the Absorbing and Float set points. Equalization is not compensated in the FLEXmax."

So what I was observing is normal. I am once again impressed by and grateful for the OB technical support folks.

I remember reading that also but didn't "apparently" pay enough attention to your original post. I missed that you were talking about equalization. I am still thankfull for your follow through and comunication as maby it will be ingrained in my small brain from this point forward.Thanksgww

PS I do hate that I just bought a new fm80 and I have to go online to read the manual as it doesn't come with one.

I tried using the RTS sensor on my Mx60 but had to give up. It worked perfectly in the sense that it reduced the absorb voltage set point exactly as designed (and even recommended by Trojan) for the slightly elevated ambient temp. However, the reduced absorb voltage resulted in an abnormally low SPg. and no amount of absorb time brought the state of charge above 85%. This was on brand new Trojan T105 batteries. I was mystified since the old batteries had worked fine before I bought the RTS but I figured I might get longer life if I "did it right" with the new ones.Finally, after posts to Outback and other forums, a consult with Trojan support confirmed that it is critical that the SPg. be brought up to full charge (1.28) regardless of the temperature. So the RTS is disconnected and the new batteries are performing perfectly. I really would like to use the RTS but the result hasn't worked, at least for me. I'd really like to hear from someone who is using the RTS and isn't experiencing reduced SPg.

Curious to know what kind of temperatures you were reaching that would keep the batteries from properly charging.

Thanks!Luke

mhtmr wrote:I tried using the RTS sensor on my Mx60 but had to give up. It worked perfectly in the sense that it reduced the absorb voltage set point exactly as designed (and even recommended by Trojan) for the slightly elevated ambient temp. However, the reduced absorb voltage resulted in an abnormally low SPg. and no amount of absorb time brought the state of charge above 85%. This was on brand new Trojan T105 batteries. I was mystified since the old batteries had worked fine before I bought the RTS but I figured I might get longer life if I "did it right" with the new ones.Finally, after posts to Outback and other forums, a consult with Trojan support confirmed that it is critical that the SPg. be brought up to full charge (1.28) regardless of the temperature. So the RTS is disconnected and the new batteries are performing perfectly. I really would like to use the RTS but the result hasn't worked, at least for me. I'd really like to hear from someone who is using the RTS and isn't experiencing reduced SPg.

Marty is in Mexico, and it is possible, that the Absorb voltage should have been set a bit higher than it was, but perhaps, having no Temperature Compensation and the assumed ambient temps (possibly) above Trojan's Reference temperature of 80 degrees F nominal, that the batteries really needed a higher (non-compensated) Absorb AND Float voltage.

Also, about in the time-frame noted by him, Trojan did increase the SG of some of their batteries from about 1.265 to 1.277 - 1.280. This did not affect the Ind line, but, certainly, their L-16s, and quite possibly on the GC-2 (T-105) batteries as well. This could have been an additional factor ... since Marty noted a charging difference with his "new" GC-2s,

Just some guessing, he did note a " slightly elevated ambient temp" when trying to charge the new batteries. FWIW, Vic